1. Field of the Invention
The invention relates to processes of treating agricultural plants with gibberellin and to gibberellin-based preparations for realizing such processes.
The invention can be used to enhance the productivity of both seedless and seed-bearing varieties of grape with a tendency to parthenocarpic berry formation, of vegetable crops, such as tomatoes, eggplants, peppers, melon crops, fruit-bearing plants, such as apple-trees, pear-trees in palmette and meadow orchards, and citrus plants.
The present invention is particularly efficient in hot-bed farming.
2. Description of the Prior Art
The productivity of cultivated plants is known to be increased with the use of various growth stimulators.
For example, there are known growth stimulators based on organic acids, such as 2,4,5-trichlorophenoxyacetic acid, 2,4-dichlorophenoxyacetic acid, 6-indoleacetic acid, indolebutyric acid, .alpha.-naphtylacetic acid, 2,4,5-trichlorophenoxy-.alpha.-propionic acid.
However, the preparations based on one or more of the above-cited growth stimulators did not find wide application in plant raising, since many of them showed little efficiency in stimulating fruit formation and some of them, such as 2,4-dichlorophenoxyacetic acid, adversely effect morphogenesis of treated plants.
Cytokinins, such as 6-furfurylamino purine, 6-benzylamino purine are also known to be growth stimulators. However, cytokinin-based preparations are active only in the presence of auxins, such as 6-indoleacetic acid or indolebutyric acid. The action of cytokinins on the fruictification and growth of fruit of cultivated plants has not been adequately studied and therefore these plant hormones did not find wide application in plant raising either.
Of all the known growth stimulators most widely used are gibberellins, mainly gibberellic acid. Gibberellins are obtained by microbiological synthesis from the fungi of Fusarium genus.
Commonly known methods of stimulating fructification and fruit growth of cultivated plants with the use of gibberellin (see, for example, R. J. Weaver, Plant Growth Substances in Agriculture. University of California, Davis, W. H. Freeman and Co., 1972) are based on spraying the blossom clusters with or dipping them into low-concentration liquid preparation of gibberellin.
This preparation contains from 0.002 to 0.01 wt.% of gibberellin, from 1 to 2 wt.% of ethanol, the balance being water.
Spraying of blossom clusters inevitably results in gibberellin getting on vegetative organs adjacent to the cluster and the nutrient elements are thus wasted on the growth of these organs.
Dipping of blossom clusters into gibberellin solution is therefore a more preferable technique of applying this stimulator for cultivated plant fruitification. However, solution drops trickling down from the blossom clusters may produce the same adverse effect as the spraying, and the time required for the excess gibberellin solution to flow down back into the vessel into which the blossom cluster has been dipped materially reduces the treatment efficiency.
Another adverse effect observed in spraying the blossom clusters with or dipping them into a solution is the reduction of crop quality because of the dissimilarity of the fruits formed.
When spraying technique is employed, this dissimilarity is caused by the impossibility of attaining equally uniform treatment of all the florets in a cluster with a small portion of the solution. Increasing the amount of the solution in spraying the blossom clusters dipping them into the solution does not bring about an adequate increase in the similarity of the fruits being formed, since the excess solution flows gradually down from the upper florets to the lower ones and partially to other parts of the plant.
Another disadvantage of spraying and dipping is the formation of solution drops on individual florets or other parts of the plant.
Under the conditions of intensive insolation these solution drops may cause burns of the florets and other parts of the plant whereon they fall. Treatment of blossom clusters is therefore preferably to be performed in the mornings or in the evenings, which prevents the considered method from being used over large areas.
Still another disadvantage, which is especially specific for the technique of spraying blossom clusters, is a higher consumption (as compared to physiological demand of gibberellin a part of which flows down onto the soil and is not assimilated by the plant.
It is also to be noted that in spraying and dipping the blossom clusters, gibberellin not assimilated by them remains in dry form on the fruits, which is undesirable from the sanitary-hygienic point of view.
In areas with water deficiency or in case if gibberellin solution is prepared for away from the place of its utilization, a disadvantage resides in a relatively high water requirement for the preparation of said solution, the consumption of water being from 300 to 800 l per hectare.